public async Task EnsuresNonNullArguments()
            {
                var client = new ObservableOrganizationMembersClient(Substitute.For<IGitHubClient>());

                await AssertEx.Throws<ArgumentNullException>(async () => await client.GetPublic(null));
                await AssertEx.Throws<ArgumentException>(async () => await client.GetPublic(""));
            }
            public void RequestsTheCorrectUrl()
            {
                var gitHubClient = Substitute.For<IGitHubClient>();
                var client = new ObservableOrganizationMembersClient(gitHubClient);

                client.GetPublic("org");

                gitHubClient.Connection.Received(1).GetAsync<List<User>>(
                    new Uri("orgs/org/public_members", UriKind.Relative), null, null);
            }